1. Field of the Invention
The present invention relates generally to a cognitive UWB system and a cognitive UWB data communication method and, more particularly, to a cognitive UWB system and a cognitive UWB data communication method, which generate pulses using mask information and channel environment information, so that they can provide universal flexibility satisfying UWB frequency emission regulations imposed by individual countries, use unoccupied frequency bands in an UWB band so as to avoid interference with other systems, flexibly use the unoccupied frequency bands using channel detection and specific information by dividing a UWB frequency into a plurality of sub-frequency bands, improve transmission rates and communication quality using more sub-frequency bands when needed, and promote the efficiency of the use of frequencies using data communication at power higher than that of the UWB frequency emission regulations without exceeding a non-interference limit.
2. Description of the Related Art
In general, a UWB communication system refers to a wireless system that aims to transmit a large quantity of digital data via a wide spectrum frequency band at very low power in a local area.
Here, since a frequency of several GHz is used and a low output pulse is generated several thousands to several million times per second, the UWB communication system can transmit a large quantity of data at a low power of approximately 0.5 m/W over a distance of 70 m, and has a high transmission rate because the capacity thereof is proportional to a bandwidth and a Signal to Noise Ratio (SNR).
Moreover, the UWB communication system can reduce the period of a pulse using a pulse having a very short width for data communication, therefore data can be transmitted at a high transmission rate. Accordingly, the UWB communication system can reduce transmission energy, has a characteristic of being robust to a multi-path environment in a place including many obstacles, and has the characteristic of being resistant to surrounding interference because a signal is spread over a wide frequency band.
However, the UWB communication system has the following problems. That is, since the UWB communication system uses a wide band, it sends data at low power at a noise level, but may interfere with other wireless systems with regard to an impulse signal. Furthermore, since respective countries use different UWB masks, the problem of frequency usage may occur upon export to and use in different countries. Moreover, the UWB communication system cannot be flexibly changed according to a channel environment.